Terpenoids: Diverse Structures and Functions in Plant Defense and Communication

This chapter explores the expansive world of terpenoids, one of the largest and most diverse classes of secondary plant metabolites. It begins by introducing the basic isoprene unit and outlining the biosynthetic pathways that lead to the vast array of terpenoid structures found in nature. The chapter then delves into the structural diversity of terpenoids, covering monoterpenes, sesquiterpenes, diterpenes, triterpenes, and other subclasses, highlighting their unique chemical properties. The text further examines the multifaceted roles of terpenoids in plant defense mechanisms, including their function as toxins, repellents, and antimicrobial agents. It also discusses their importance in plant-communication and plant-insect interactions, such as attracting pollinators or natural predators of herbivores. Case studies of well-known terpenoids like menthol, camphor, and artemisinin are presented to illustrate the ecological and pharmacological significance of these compounds. The chapter concludes by exploring the potential applications of terpenoids in agriculture, medicine, and industry, emphasizing their role in the development of new pharmaceuticals and biopesticides.